Rheostat.



No. 7|2',749. Patentod Nov. 4, |902.

G. H. WHITTINGHAM.

BHEOSTAT.

(Application led 2l, 1902.) (lo Model.)

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UNrrED STATES PATENT OEEICE.

GEORGE H. VHlTTINGHAM, OF NFV YORK, N. Y.

RH EO STAT.

SPECIFICATION :arming part of Letters Patent No. 712,749, dated November 4, 1 902.

.Application led January Zl, 1902. Serial No. 90,618. (No model.)

T0 all whom, t Duty cmwern:

Be it known that I, GEORGE H. YHITTING- HAM, a citizen of the United States, residing at New York, in the county of New York and State ofNew York, have invented certain new and useful Improvements in Rheostats, of which the following is a specieation.

This invention relates to rheostats particularly designed for heating purposes; and its object is to provide a compact construction of rheostat of this character in which the heat generated by the electric current passing through the resistance-wire will be effectively radiated and in which the terminals of the resistance-wire are located at the same end of the rheost-at, so that ready access may be had to the parts for the purpose of repairs.

The invention consistsin certain constructions, arrangements, and combinations ofthe parts hereinafter fullydescrihed and claimed, reference heilig had to the accompanying drawings, in which- Figure l is a longitudinal sectional view of the rheostat. Fig. 2 is a perspective view thereof with the several parts partially detached from each other butin juxtaposition. Fig. 3 is a detail view of the resistance device. Fig. et is an enlarged cross-section of the same looking from the left to the right 0f Fig. 3. Fig. 5 is a detail view illustrating a slightly-modified construction of resistance device.

Referring to the drawings, the letterA designates a tubular metal or other suitable radiating jacket provided at one end with a closed cap b, screwed' or otherwise detachably secured thereon, andat the other end with an open cap or collar ct, also screwed on, so that ready access may be had to the interior of the jacket at either end. The open cap or collar a has an inwardly-extending annular shoulder d surrounding a central aperture d2, and an insulating-plug c, of porcelain or the like, is fitted in said aperture and has an annular flange c interposed between the annular shoulder of said cap and the adjacent edge of the jacket A, whereby it is securely held in place, as shown in Fig. l. Said insulating-plug is also provided with terminal passages c2 for the conductors of the resistancecoil, hereinafter described.

The interior of the tubular jacket A is insulated. In this instance the insulation comprises a glass or porcelainr open-ended tube (l within the jacket and preferably of such length that when the insulating-plug c is tightly clamped by the screw-cap d against the edge of the jacket said plug will abut against one end of said glass tube and press the other end of the tube against the screwcap l) at the other end of the jacket. By this arrangement of cap a, insulating-plug c, and glass tube da simple and etfective insulation is formed to prevent any contact between the resistance-coil and the metal radiatingjacket A.

'Ihe tubular insulated radiating-jacket A contains a resistance device,one form of which is designated B (see Figs. l, 2, 3, and 4) and comprising a resistance-wire e, wound in spiral form, and two electrical couductorsfg, one of which is suitablyv attached to one end of the spiral coil and the other of which is attached to the other end of the spiral coil and is returned through the coil to that end of the latter at which the first-named conductor is attached, and the said two terminalsf g extend through the insulating-plug c to the outside of the jacket A, where they are connected to the supply-circuit in any suitable manner. Thus both terminals are at the same end of the rheostat.

Each of the conductor-wiresfg is mounted in a tubular sleeve 7L, of iireproof insulating material, such as asbestos, as best seen in Fig. 4, and it should be especially noted said conductors are wires of high conductivity in eontradistinction to the resistancewire e. Thus when a current enters by the conductor fat the outer or entrance end of the coil e the electrical units of said current will be converted into heat units through every convolution of the resistance-coil and coming out of the distant end of the coil will ow freely withoutresistance through the returnwire g of high conductivity.

To rapidly conduct the heat generated by the resistance coil c to the exterior metal jacket A, whence it can be diffused in the atmosphere by radiation, I preferably employ a filler c', of clear loose sand, which is packed closely around and within the resistance-coil and also in the space between the glass insulatin g-tube d and the metal walls of the jacket IOC A. It is to be observed that while the resistance-coil e surrounds a tubular insulatingsleeve h, through which the return-Wire g of high electrical conductivity extends, yet, as best seen in Fig. 4, there is a spacej between said tubular insulator and coil within the glass tube, which space is filled with the heatconducting filler t', whereby the entire surface of the wireof the said resistance-coil is covered by said filler, which would not be the case if the said wire were wound directly on the insulating-sleeve h.

To assemble the parts of the rheostat, the closed cap b being on one end of the metal tube or jacket A the glass tube d is inserted in the other end. The resistance device is then inserted in said glass tube, and the insulating-plug cis inserted on the terminals of the two conductorsfg, and the cap or collar a is screwed on the jacket and clamps the insulating-plug c in place. The closed cap b is then removed and the heat-conducting filler i inserted from that end of the jacket and packed therein, after which the said screwcap b is screwed back into place. To obtain access at any time to the resistance device B,

. it is only necessary to unscrew the cap or collar a., -a'nd the entire resistance device may then be readily Withdrawn.

This invention is manifestly not limited to a resistance device having the single return- Wire of high conductivity, as illustrated in Figs. l, 2, 3, and 4. For instance, as shown in Fig. 5, the resistance device B' has a plurality of return-wires g', secured to dierent convolutions of the coil e, with all their terminals passing through an insulating-plug in the manner hereinbefore set forth in respect to the resistance device B. With this arrangement the circuit of the rheostat may belengthened or shortened, as desired, by any suitable switch device.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A device of the character described, comprising an insulating-sleeve; a resistance-coil surrounding said sleeve; and an electrical conductor connected to one end of said coil and extending through said coil and through said-sleeve, the two terminalsof the coil being thereby at the same end of the coil.

2. A device of the character described, comprising an insulating-sleeve a resistance-coil of wire surrounding said sleeve; anda returnwire of relatively highl conductivity connected to said coil and extending through the coil and through the said sleeve, as set forth.

3. The combination of aninsulating-sleeve; a resistance-coil surrou nding said insulatingsleeve with its convolutions spaced therefrom; and a return-wire of relatively high conductivity connected to said coil and eX- tending therethrough and through said sleeve, as set forth.

4. The combination of a radiating-jacket; a resistance-coilin said jacket; a return wire or conductor connected to said coil and extending therethrough; an insulating-sleeve in which said conductor is mounted, said sleeve beingspaced from the convolutions of the coil; and a heat-conducting filler in said jacket and filling the space between the coil and the said sleeve, as set forth.

5. The combination of a radiating-jacket; a cap for one end of said jacket, said cap being provided with an inwardly-extending annular shoulder; an insulating-plug extending through said cap and provided with an aunular flange interposed between said annular shoulder and the adjacent edge of said jacket; and a resistance-coil within said jacket and all of whose terminals pass through said plug, as set forth.

6. The combination of a radiating-jacket; a cap or collar for'one end of said jacket; an insulating-plug extending through said cap and provided with a plurality of passages; and a resistance-coil within said jacket and having all its terminals passing through the passages of said plug, as set forth.

In testimony whereof I attix myvsignature in the presence of two witnesses.

GEORGE H. WH ITTINGI-IAM.

Witnesses:

FREDERICK S. STITT, CHARLES L. VIETsoH. 

